1.Only a fraction of the genes in a cell are expressed at any one time. The variety of gene expression profiles characteristic of different cell types arise because these cells have distinct sets of transcription regulators. Some of these regulators work to increase transcription, whereas others prevent or suppress it.
2.Normally, transcription begins when an RNA polymerase binds to
a so-called promoter sequence on the DNA molecule.
3.This sequence is almost always located just upstream from the
starting point for transcription (the 5' end of the DNA), though it
can be located downstream of the mRNA (3' end).
4.DNA sequences, known as enhancer sequences, also play an
important part in transcription by providing binding sites for
regulatory proteins that affect RNA polymerase activity.
5.Binding of regulatory proteins to an enhancer sequence causes a
shift in chromatin structure that either promotes or inhibits RNA
polymerase and transcription factor binding.
6.A more open chromatin structure is associated with active gene
transcription.In contrast, a more compact chromatin structure is
associated with transcriptional inactivity.
7.Some regulatory proteins ffect the transcription of multiple genes. This occurs because multiple copies of the regulatory protein binding sites exist within the genome of a cell. Consequently, regulatory proteins can have different roles for different genes, and this is one mechanism by which cells can coordinate the regulation of many genes at once.
help please 2. Why do we see that each cell is only expressing a small fraction...
Help please 7. How does the formation of a ring species lead to speciation in the absence of allopatry? 2. Why do we see that each cell is only expressing a small fraction of the genes in it's genome at any given time?
Help please 1. Explain the difference between isotopes and biomarkers and how each can be used to identify characteristics of fossils. 2. Why do we see that each cell is only expressing a small fraction of the genes in it's genome at any given time? 3. Why can't natural selection alone drive dominant alleles to fixation within a population?
Why do we only see a small portion of the earth’s magnetic field?
we've learned that mitochondria and chloroplasts have their own DNA, BUT ONLY A SMALL FRACTION compared to the prokaryotes that biologists have identified as their closest, free-living ancestors. Most of the mitochondrion genome has been transferred to the host nucleus. Why do you think the mitochondria still has the remnants of a few genes and didn't transfer all its genome to the host nucleus?
Why would a bacteria cell benefit from expressing the lac operon only in the presence of lactose? 1. The cell benefits by limiting the energy spent on the expression of the lac operonA. 2. The cell needs the lac operon to be expressed in order to obtain energy from lactose. 3. The cell doesn’t benefit, it would be better if the lac operon were expressed all of the time. 4.The production of lac operon proteins requires energy, but their production...
Question: This is a small discussion post please help this is discussion question What do you think about t... this is a small discussion post please help this is discussion question What do you think about the “language acquistion device?” Do you think we learn to speak based on reinforcement or is there a neurological device? Most psycholinguistics today, would agree that it's a combination of both. Share your opinions as well as your experiences with children learning verbal behavior...
IN JAVA PLEASE HELP! ALSO PLEASE ADD COMMENTS Summary Build two classes (Fraction and Fraction Counter) and a Driver for use in counting the number of unique fractions read from a text file. We'll use the ArrayList class to store our list of unique Fraction Counters. Rather than designing a monolithic chunk of code in main like we did in the previous homework, we'll practice distributing our code into containers (called classes) that you will design specifically to tackle this...
) Why do we not see any evidence (at birth or in spontaneous abortions) of chromosome 1 monosomies or trisomies? B) Do you think they occur? Explain.
Can any one explain the claim for me please? I cannot see why thats true as p is greater than 1, surely we will have extra terms. To me its like it is calming (a+b)^2 <= a^2 + b^2 Any help will be much appreciated. Let Take f, g E B: then for any λ E (0, 1) we have CL Let Take f, g E B: then for any λ E (0, 1) we have CL
Why do we add fetal bovine serum to cell culture media? (2-3 paragraphs)